This site is a scandal. Always, AT&T ask me to test on this site. When I have terribly slow and connections dropping and can't even refresh any page and load just a html site, this would test for 2.3mbps to 2.5mbps. Other site tested my speed as 46kbps to 400kbps. But, this site always give the good result.
This should be scandal for some testing takes as long as 2 minutes and still it says 2.5mbps. May be they are only testing the burst speed?. But, ISP are using it for their advantage.